Paper carriage escapement device for typewriters



Nov. 2, 1937. F. EIBERT 2,097,834

PAPER CARRIAGE ESCAPEMENT DEVICE FOR TYPEWRITERS Filed April 16, 1934 1 [well/0r Fritz EiBER Patented Nov. 2, 1937 UNITE STATES PATENT OFFICE PAPER CARRIAGE ESCAPEMENT DEVICE FOR TYPEWRITERS Fritz Eibert, Munich,

Germany, assignor to In Germany 5 Claims.

For returning the parts of the typewriter moved forward by the striking of the keys, such as universal bar, escapement lock and the like, and for returning the struck type lever, separate tension or compression springs are employed. The striking of the keys is, however, rendered more difficult hereby and the individual parts are subject to considerable wear owing to the friction from pressure. It been proposed to utilize the carriage pull spring for assisting the return movement of the type lever and with this object in View it has been proposed to provide the pawl with an inclined or Wedge surface, on which the ratchet wheel tooth, freed from the retaining pawl is allowed to act in order to accelerate the return movement of the struck type lever. This arrangement does not, however, give entire satisfaction because it necessitates considerable movement of the pawl carrier during the striking of the key, if the wedge surface is to become operative at all. This considerable movement results, however, in a restriction of the writing speed. Moreover, the wedge surfaces brought into the path of the liberated ratchet wheel tooth and on which the tooth slides cause frictional and checking resistance because the direction of movement of the universal bar, which is to be obtained is at right angles to the direction of movement of the ratchet wheel tooth along 30 which the wedge surface slides.

The present invention eliminates the above mentioned objections, in that the undiminished force of the carriage pull spring is utilized for the return of all parts moved in the one direction by striking a key and particularly for returning the struck key lever into its initial position. The typewriter thus has a writing speed which is only restricted by the efficiency of the typist, and spring action opposing the striking of the key is no longer required.

This end is reached in this way, that the ratchet wheel tooth, which is liberated by the striking of the key, does not, as was formerly used, act upon a displacement pawl, but on the arm of a lever arrangement, of which one or more fulcrums are mounted in the machine outside the escapement element and the universal bar.

For example the liberated ratchet wheel tooth can be made to act directly or indirectly on one arm of an elbow lever, the other arm of which returns the universal bar into its position of rest. This elbow lever may, however, be mounted on the universal bar in the machine so that it is possible to effect the returning movement of the April 19, 1933 universal bar. One end of the elbow lever is loosely connected by means of a catch pin with the retaining pawl or its carrier so that the elbow lever can lift the retaining pawl and bring it to in front of the next ratchet wheel tooth to be checked. As this is compulsorily efiected, a perfect, step-by-step escapement of the paper carriage is ensured and a jumping of the carriage rendered impossible.

By this arrangement the force of the carriage pull spring is transmitted more rapidly and without loss of power caused by friction on to the universal bar and thus to the type lever which has been struck. The period during which the ratchet wheel tooth acts is shortened relatively to the action on a wedge surface and consequently an increased speed is imparted to the escapement operation. A further advantage consists in that the amplitude of the retaining pawl movement can be reduced to a minimum so that the retaining pawl or its carrier, in order to liberate the locked tooth, need only be moved immediately before the type strikes the platen. This arrangement, however, does not as in the known constructions, compel the part of the escapement mechanism, hitherto mostly the displacement pawl, which takes up the liberated ratchet wheel tooth, to move a corresponding distance. On the contrary, the elbow lever, which undertakesv the duty of the former pawl, is preferably allowed to participate in the full amplitude of the movement of the universal bar, in order to fully utilize for the return movement of the universal bar the force imparted to it.

By this movement of the elbow lever it is also possible at the same time to move the retaining pawl away from the checked ratchet wheel tooth. Moreover, a separate thrust rod may also be fitted on the universal bar for this purpose, which rod comes into contact with the carrier of the retaining pawl shortly before the termination of the universal bar movement and thus releases the checking.

Anembodiment of the invention is illustrated by way of example in the accompanying drawing, in which:-

Fig. 1 shows in top plan view an escapement device in position of rest with the type lever segment I, the universal bar 2, the elbow lever 3 pivotally mounted on an axle 4 in the machine and having two arms 5 and 6, its connection 1 with the universal bar 2 and its connection with the pawl carrier l0 by a pin 8 engaging in an aperture 9, and the retaining or looking pawl II which checks a ratchet wheel tooth l2, another Fig. 4 depicts a somewhat fragmentary View of the bell crank lever and of the universal bar shown in Figs. 1 and 2.

Fig. 5 is a perspective and fragmentary view of the pawl carrier and detaining pawl illustrated in Figs. 1 and 2.

Fig. 6 is a side elevational view, also fragmentary, of the escapement showing the pawl and the ratchet wheel in working position.

The escape nent operates as follows:-

By the striking of a key the universal bar 2 is moved away from the segment I by the type lever swinging towards the platen; thus, the elbow lever 3 is rocked by its arm 5. Shortly before the universal bar reaches its extreme position, the thrust rod l5 comes into contact with the pawl carrier Ill and moves the same so far that the checked tooth I2 is liberated by the retaining pawl H. The elbow lever 3 has in the meantime moved so far that the nose I4 on its arm 6 is situated in front of the liberated ratchet wheel teeth. This tooth, being under the influence of the carriage pull spring, acts on the nose 14 of the elbow lever arm 6 in the direction of the arrow b (Fig. 2) and moves the same back into its initial position, the ratchet wheel tooth l2 sliding off the nose l4. Shortly before the termination of this movement the pin 8 on the elbow lever arm 6 which projects into the aperture 9 .in the pawl carrier I0 moves this carrier together with the retaining pawl H and compulsorily brings this pawl to in front of the next following ratchet wheel tooth (Fig. 1), thereby arresting the paper carriage until the next key is struck.

I claim: 7

1. In a typewriting machine having key and type levers and a spring-powered ratchet wheel, the combination comprising a universal bar actuated by depression of a key, a pawl carrier actuated by said universal bar, a detaining pawl mounted on said pawl carrier normally engaged by a tooth of said ratchet wheel, a bell crank lever pivoted on a stationary part of said typewriting machine having one of its ends connected to said universal bar and its other end protruding into the path of. a teeth of said ratchet wheel whereby said lever is displaced and said universal bar and said key lever are returned to their normal position of rest when the end of said lever is engaged by one of the teeth of said ratchet wheel.

2. In a typewriting machine having key and typelevers and a spring-powered ratchet wheel, the combination comprising a universal bar actuated by depression of a key lever, a pawl carrier actuated by said universal bar, a detaining pawl mounted on said pawl carriernormally engaged by a tooth of said ratchet wheel, a bell crank lever pivoted in a pin arranged on a stationary part of said typewriting machine, said lever having one of its ends connected to said universal bar and having a surface at its other end at an angle to the direction of movement of said ratchet wheel and adapted to be moved into operative position when said universal bar is actuated, whereby said surface is engaged and displaced by a tooth of said ratchet wheel and said universal bar and said key lever are returned to their normal position of rest when said ratchet wheel is in movement.

3. In a typewriting machine having key and type levers, a spring-powered ratchet wheel and a universal bar with associated pawl carrier and detaining pawl actuated by depression of a key lever, the improvement which comprises in combination a pivoted bell crank lever having one arm adapted to coact with said universal bar, a displacement pawl integral with the other arm of said lever, and means operatively connecting the last mentioned arm of said bell crank lever with said pawl carrier to return said detaining pawl into operative position when said displacement pawl is actuated whereby said displacement pawl is engaged by a tooth of said ratchet wheel and said bell crank lever is actuated to return said universal bar and said key lever to their normal position of rest when the ratchet wheel is released by said detaining pawl.

4. In a typewriting machine having key and type levers and a spring-powered ratchet wheel, the combination comprising a universal bar actuated by depression of a key lever, a thrust rod connected to said universal bar, a pawl carrier capable of being displaced by said thrust rod, a detaining pawl mounted on said pawl carrier normally engaged by a tooth of said ratchet wheel and adapted to release said tooth when said carrier is displaced by said thrust rod, a pivoted bell crank lever having one of its ends operatively associated with said universal bar, a displacement pawl integral with the other end of said bell crank lever normally disengaged from the teeth of said ratchet wheel, whereby said detaining pawl releases said teeth of said ratchet wheel when said universal bar and said thrust rod are actuated and subsequently said displacement pawl is engaged and displaced by said released tooth of said ratchet wheel and returns said universal bar and said key lever to their normal position of rest.

5. In a typewriting machine having key and type levers and a spring-powered ratchet wheel, the combination comprising a universal bar actuated by depression of a key, a thrust rod connected to said universal bar, a pawl carrier having a slot in the direction of movement of said ratchet wheel and capable of being displaced by said thrust rod, a detaining pawl mounted on said pawl carrier normally engaged by a tooth of said ratchet wheel, a pivoted bell crank lever having one of its ends operatively associated with said universal bar, a displacement pawl normally disengaged from the teeth of said ratchet wheel and a catch pin engaging said slot in the pawl carrier at the other end of said lever, whereby said detaining pawl releases said ratchet wheel tooth when said universal bar and said thrust rod are actuated and subsequently said displacement pawl is engaged and displaced by said released tooth and by means of said elbow lever returns said universal bar, said key leverand said pawl carrier to their normal position of rest.

FRITZ EIBERT. 

